1. Field of the Invention
This invention relates generally to modular control valve systems, and more specifically, to improvements therein for industrial, mobile, and other market applications.
2. Description of Related Art
Referring generally, valves are devices that regulate (i.e., start, stop, or otherwise control) fluid flow using a moveable valve element (e.g., a ram, ball, cone, poppet, rotary spool, sliding spool, and the like), which allows access to or obstructs various passageways therewithin the device. Many types of valves are, of course, well-known, and the valve elements may generally be controlled manually, mechanically, pneumatically, hydraulically, magnetically, and electrically, or by various combinations thereof. In addition, the moveable valve element can be either direct-operated or pilot-operated, controlled in either an on-off or proportional fashion, and operated either without feedback or with servo-feedback.
Valves are commonly used to regulate the flow, the pressure, and the direction of a fluid, and are, accordingly, commonly classified according to three primary types of uses—namely flow control valves, pressure control valves, and directional control valves.
Flow control valves regulate fluid flow within a system. Many types of flow control valves are well-known, including, for example, ball valves, gate valves, globe valves, needle valves, and the like.
Pressure control valves, on the other hand, regulate valve pressure. Again, many types of pressure control valves are well-known, including, for example, relief valves, pressure regulating valves, and the like. Common types of pressure regulating valves (also known as unloading valves) include, for example, sequence valves (for controlling a sequence of events within a system), pressure reducing valves (for maintaining reduced pressure downstream in a system using a higher upstream pressure), and the like. In pneumatic systems, pressure regulating valves are commonly used to reduce system pressure, whereas in hydraulic systems, they are commonly used to unload pumps.
Directional control valves (also known as directional valves, selector valves, transfer valves, and control valves) direct fluid flow to various points in a valve where work will be performed. Moving the valve element back and forth within a longitudinal bore that extends through a valve housing, for example, directs the fluid flow, as will be elaborated upon. The position and speed of the valve element may be controlled by techniques well-known in the art. In pneumatic systems, tank ports (also known as return or exhaust ports) are often vented to the atmosphere, whereas in hydraulic systems, tank ports commonly return fluid flow to tank reservoirs. Directional control valves can be classified in many ways, including, for example, by their types of controlling mechanisms, specific valve functions, the number of ports in a valve housing, the number of positions of the valve elements, or the total number of flow paths provided in the valve in extreme positions. For example, a three-position directional control valve may have one central or neutral position and two extreme positions, whereby if each of the two extreme positions permits two flow paths, a total number of four flow paths are provided. Another common directional control valve classification scheme identifies the type of valve element used therewithin. For example, a sliding spool directional control valve is so-named because of the shape of the valve element that slides back and forth within the valve to cover and uncover various ports in the valve housing. Various spool areas (also known as lands) regulate where the fluids enter and exit the valve through various inlet and outlet ports in the valve housing, thereby performing said work. Many sliding spool directional control valves achieve sealing by closely machining precision-fittings between the sliding spool and longitudinal bore within the valve.
Valves are also commonly classified as two-way, three-way, and four-way valves.
Two-way valves regulate fluid flow through one inlet and one outlet port. More specifically, in a two-way sliding spool directional control valve, the sliding spool moves back and forth, and as it does so, it either allows fluid to flow or not flow into the valve housing. For example, in an “open” position, fluids enter the valve housing from the inlet port, then flow around the shaft of the sliding spool, and then exit through the outlet port, whereas in a “closed” position, the fluid is altogether precluded from entering the valve housing.
Three-way valves regulate fluid flow through one pressure port P, one tank port T, and one working port A (also known as a cylinder port). More specifically, in a three-way sliding spool directional control valve, the sliding spool is operated in one direction, whereby either a return load or a spring acting on the sliding spool returns the same to an original position after the motive force is removed. For example, if the force of a fluid under pressure alters the position of the sliding spool within the longitudinal bore, it may also simultaneously compress a spring at a distal end of the valve housing, whereby once the motive force is removed, the spring returns the sliding spool to its original position within the longitudinal bore. Accordingly, the valve housing connects either i) P to A, or ii) T to A.
Four-way valves regulate fluid flow through one pressure port P, one tank port T, and two working ports A, B. More specifically, in a four-way sliding spool directional control valve, the sliding spool is operated in both directions, whereby motive forces control the position of the sliding spool from both sides of the valve housing. Accordingly, the valve housing connects either i) P to A and T to B, or ii) T to A and P to B.
Valves with even greater numbers of flow direction are also well-known. Still further, the following are also well-known: direct operated valves, such as DO3, DO5, DO5H, DO8, and DO10, and the like; pilot controlled valves, which use a pilot spool to control the sliding spool; on-off valves, including wet and dry armature on-off valves; proportional control valves; servo (also known as feedback) valves; and many techniques for pneumatic, hydraulic, and other valve amplification.
Many other variations and varieties of the foregoing are also well-known in the art, and hereby contemplated.